1. Field of the Invention
The present invention relates to thermal transfer ribbons for peripheral printers and more particularly to thermal transfer color-variable ribbons for peripheral printers.
2. Description of Prior Art
Conventional color ribbons used in thermal transfer printing processes are shown in FIG. 1. Ribbon prepared by this method usually contains only a single layer of a thin film material which produces a selected color independent of viewing angle. The conventional ribbon often contains a sensible dye, or pigment material in a binding material, e.g., thermoplastic resin. The "ink" is transferred to the receiving medium through dye diffusion into the receiving medium or solid wax binding to the surface of the receiving medium.
Conventional ribbons have the following disadvantages. First, film stress, which exists in the single layer of thin film material, contributes to the fragility of the transferred film during the process and on the printed documents as well. Second, colored documents prepared in accordance with this technique may be duplicated with advanced image simulating processes and therefore are susceptible to high-tech counterfeiting.